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Anthropogenic noise is globally increasing in aquatic ecosystems, and there is concern that it may have adverse consequences in many fish species, yet the effects of noise in field settings are not well understood. Concern over the applicability of laboratory-conducted bioacoustic experiments has led to a call for, and a recent increase in, field-based studies, but the results have been mixed, perhaps due to the wide variety of techniques used and species studied. Previous reviews have explored the behavioral, physiological, and/or anatomical costs of fish exposed to anthropogenic noise, but few, if any, have focused on the field techniques and sound sources themselves. This review, therefore, aims to summarize, quantify, and interpret field-based literature, highlight novel approaches, and provide recommendations for future research into the effects of noise on fish. [ABSTRACT FROM AUTHOR]

Determining the mechanisms by which genes are switched on and off during development is a key aim of current biomedical research. Gene transcription has been widely observed to occur in a discontinuous fashion, with short bursts of activity interspersed with periods of inactivity. It is currently not known if or how this dynamic behaviour changes as mammalian cells differentiate. To investigate this, using an on-microscope analysis, we monitored mouse α-globin transcription in live cells throughout erythropoiesis. We find that changes in the overall levels of α-globin transcription are most closely associated with changes in the fraction of time a gene spends in the active transcriptional state. We identify differences in the patterns of transcriptional bursting throughout differentiation, with maximal transcriptional activity occurring in the mid-phase of differentiation. Early in differentiation, we observe increased fluctuation in transcriptional activity whereas at the peak of gene expression, in early erythroblasts, transcription is relatively stable. Later during differentiation as α-globin expression declines, we again observe more variability in transcription within individual cells. We propose that the observed changes in transcriptional behaviour may reflect changes in the stability of active transcriptional compartments as gene expression is regulated during differentiation. Here the authors observe transcription dynamics in real-time throughout erythropoiesis by combining PP7 tagging of α-globin RNA transcripts and "on-microscope" cell staging. They show how the pattern of transcriptional bursting changes during differentiation, with variability in individual cells significantly reduced at the peak period of gene expression. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented on transient visual loss due to reversible 'pending' central retinal artery occlusion.

In the underwater environment, sound propagates both as a pressure wave and as particle displacement, with particle displacement dominating close to the source (the nearfield). At the receptor level, both the fish ear and the neuromast hair cells act as displacement detectors and both are potentially stimulated by the particle motion component of sound sources, especially in the nearfield. A now common way to test 'hearing' in fish involves auditory evoked potentials (AEPs), with recordings made from electrodes implanted near the auditory brainstem. These AEP recordings are typically conducted in enclosed acoustic environments with the fish well within the nearfield, especially for lower frequencies. We tested the contribution of neuromast hair cells to AEP by first testing intact goldfish (Carassius auratus), then ablating their neuromasts with streptomycin sulphate - disabling superficial and canal neuromasts - and retesting the same goldfish. We performed a similar experiment where only the superficial neuromasts were physically ablated. At 100 and 200 Hz, there was a 10-15dB increase in threshold after streptomycin treatment but no significant difference at higher frequencies. There was no difference in threshold in control fish or in fish that only had superficial neuromasts removed, indicating that the differential responses were driven by canal neuromasts. Taken together, these results indicate that AEP results at lower frequencies should be interpreted as multimodal responses, rather than as 'hearing'. The results also suggest that in natural situations both the ear and lateral line likely play an integrative role in detecting and localising many types of 'acoustic' stimuli. [ABSTRACT FROM AUTHOR]

The auditory abilities of the round goby Neogobius melanostomus were quantified using auditory evoked potential recordings, using tone bursts and conspecific call stimuli. Fish were tested over a range of sizes to assess effects of growth on hearing ability. Tests were also run with and without background noise to assess the potential effects of masking in a natural setting. Neogobius melanostomus detected tone bursts from 100 to 600 Hz with no clear best frequency in the pressure domain but were most sensitive to 100 Hz tone stimuli when examined in terms of particle acceleration. Responses to a portion of the N. melanostomus call occurred at a significantly lower threshold than responses to pure tone stimulation. There was no effect of size on N. melanostomus hearing ability, perhaps due to growth of the otolith keeping pace with growth of the auditory epithelium. Neogobius melanostomus were masked by both ambient noise and white noise, but not until sound pressure levels were relatively high, having a 5-10 dB threshold shift at noise levels of 150 dB re 1 µPa and higher but not at lower noise levels. [ABSTRACT FROM AUTHOR]

The larval phase of most species of coral reef fishes is spent away from the reef in the pelagic environment. At the time of settlement, these larvae need to locate a reef, and recent research indicates that sound emanating from reefs may act as a cue to guide them. Here, the auditory abilities of settlement-stage larvae of four species of coral reef fishes (families Pomacentridae, Lutjanidae and Serranidae) and similar-sized individuals of two pelagic species (Carangidae) were tested using an electrophysiological technique, auditory brainstem response (ABR). Five of the six species heard frequencies in the 100–2,000 Hz range, whilst one carangid species did not detect frequencies higher than 800 Hz. The audiograms of the six species were of similar shape, with best hearing at lower frequencies between 100 and 300 Hz. Strong within-species differences were found in hearing sensitivity both among the coral reef species and among the pelagic species. Larvae of the coral reef species had significantly more sensitive hearing than the larvae of the pelagic species. The results suggest that settlement-stage larval reef fishes may be able to detect reef sounds at distances of a few 100 m. If true hearing thresholds are lower than ABR estimates, as indicated in some comparisons of ABR and behavioural methods, the detection distances would be much larger. [ABSTRACT FROM AUTHOR]

Earlier reports on homozygous sickle cell (SS) disease have been biased by severely affected cases. The Jamaican clinic which seeks to avoid such bias has 102 patients surviving beyond 60 years. The objective of this study was to examine the features of elderly cases and assess factors determining survival and the behaviour of this disease with advancing age. A retrospective review of all cases and prospective assessment in survivors was conducted at The Sickle Cell Clinic at the University of the West Indies, Kingston, Jamaica previously operated by the MRC Laboratories. All patients with SS disease born prior to December 31, 1943 who would, by January 2004, have passed their 60th birthday were traced and their current status ascertained. The molecular and clinical features were assessed and observations on the clinical behaviour of the disease and of haematology and biochemistry are presented. Of the 102 patients, 58 had died, four had emigrated and 40 were alive, resident in Jamaica and aged 60–87 years. Survival was associated with female gender and higher foetal haemoglobin but not with alpha-thalassaemia or beta-globin haplotype. A tendency to familial clustering among elderly survivors did not reach statistical significance. Painful crises ameliorated with age and there was a benign course in pregnancy. Mean haemoglobin levels fell with age and were generally associated with rising creatinine levels indicating the importance of renal failure. Elderly survivors present some features of intrinsic mildness but also manifest age-related amelioration of painful crises and falling haemoglobin levels from progressive renal damage. [ABSTRACT FROM AUTHOR]

Recent work in the α thalassaemia field has started to provide some indication of the mechanisms involved in the very high frequency of the different forms of α thalassaemia among the populations of tropical countries, and, at the same time, is starting to define at least some of the mechanisms for its remarkable phenotypic heterogeneity. These diseases continue to provide extremely valuable models for the better understanding of the regulation of the α globin genes, and for human molecular pathology in general. The much less common disorders, ATR-16 and ATR-X are also providing valuable information about the spectrum of molecular lesions associated with different forms of mental retardation and about the molecular mechanisms involved in their varying phenotypes. [ABSTRACT FROM AUTHOR]

Auditory and olfactory abilities of settlement-stage larvae of the coral trout Plectropomus leopardus (Pisces: Serranidae) were tested electrophysiologically to determine if these senses are sufficiently developed to aid larvae in detection of settlement habitats on coral reefs. Plectropomus leopardus larvae detected sounds from 100 to 2000 Hz with hearing most sensitive at the frequencies of 100, 200 and 600 Hz. The olfactory response of P. leopardus was similar for the two amino acids tested and for the water conditioned by conspecifics. Auditory and olfactory abilities of P. leopardus are well developed at settlement-stage, and apparently sufficient to detect auditory and olfactory cues from reefs. [ABSTRACT FROM AUTHOR]

Temperature is a vital sign which can be measured using various types of clinical thermometers. Pulmonary artery temperature is considered the 'gold standard', but this measurement is not usually clinically practical. There is currently no consensus for optimal alternative site or equipment. This research compares 178 simultaneous measurements from S clinical areas, using two types of thermometers: tympanic and no-touch temporal. No-touch thermometers were all set to oral equivalent. Tympanic thermometers were adjusted to either oral (n=105) or core (n=73) equivalent. Maximum acceptable difference was identified as 1°C. Two data sets (oral/core; oral/oral) were analysed using Bland-Altman method on Excel programmes, comparing all thermometers and separating oral and core-equivalent tympanics. The two thermometers were found not to be equivalent. As a simple comparison between two thermometers, this research cannot identify which thermometer is more accurate. [ABSTRACT FROM AUTHOR]

Temperature is a vital sign which can be measured using various types of clinical thermometers. Pulmonary artery temperature is considered the 'gold standard', but this measurement is not usually clinically practical. There is currently no consensus for optimal alternative site or equipment. This research compares 178simultaneous measurements from 5 clinical areas, using two types of thermometers: tympanic and no-touch temporal. No-touch thermometers were all set to oral equivalent. Tympanic thermometers were adjusted to either oral (n=105) or core (n=73) equivalent. Maximum acceptable difference was identified as 1 degreesC. Two data sets (oral/core; oral/oral) were analysed using Bland-Altman method on Excel programmes, comparing all thermometers and separating oral and core-equivalent tympanics. The two thermometers were found not to be equivalent. As a simple comparison between two thermometers, this research cannot identify which thermometer is more accurate. [ABSTRACT FROM AUTHOR]

We evaluated the effects of past and future trends in temperature and discharge in the Fraser River on the migratory performance of the early Stuart population of sockeye salmon . Fish of lower condition exhibited disproportionately higher mortality during the spawning run, elucidating a critical link between energetic condition and a fish's ability to reach the spawning grounds. We simulated spawning migrations by accounting for energetic demands for an average individual in the population from the time of entry into the Fraser River estuary to arrival on the spawning grounds (about 1,200 km upstream) and estimated energy expenditures for the average migrant during 1950-2001. The model output indicates relatively high interannual variability in migration energy use and a marked increase in energy demands in recent years related to unusually high discharges (e.g., 1997) and warmer than average water temperature (e.g., 1998). We examined how global climate change might effect discharge, water temperature, and the energy used by sockeye salmon during their spawning migration. Expected future reductions in peak flows during freshets markedly reduced transit time to the spawning ground, representing a substantial energy savings that compensated for the effect of the increased metabolic rate resulting from exposure to warmer river temperatures. We suggest that such watershed-scale compensatory mechanisms may be critical to the long-term sustainability of Pacific salmon, given expected changes in climate. However, such compensation will probably only be applicable to some stocks and may be limited under extremely high temperatures where nonenergetic factors such as disease and stress may play a more dominant role in defining mortality. Our results further indicate that a long-term decline in the mean mass of adult sockeye salmon completing their marine residency could erode their migratory fitness during the river migration and hence jeopardize the sustainability of sockeye salmon and the fishery that targets them. [ABSTRACT FROM AUTHOR]

This paper reports on an evaluation of the role and contribution of outreach in the management of the critically ill ward patient using Stake's Responsive Model (Stake, 1975) and case study methodology (Simons, 1980). Twenty cases were examined, purposefully sampling all staff involved in the case identified by an initial interview with the outreach nurse. In total, 80 interviews were carried out, 20 with the outreach nurses and 54 with other members of health care teams involved in the cases, and six further targeted in-depth interviews with senior anaesthetic and nursing staff. The outreach contribution which emerged from the data analysis consisted of four core categories: action (getting things done, getting decisions made and following through), focus and vision (concentrating on one patient and having a vision of what action was needed to meet their care needs), orchestration (a communication and co-ordinating role) and expertise (bringing critical care skills and experience to the bedside). These categories were validated and developed in the six in-depth interviews. Three themes emerged from the data describing aspects of the acute care context in which outreach operates. The interviews revealed a battleweary workforce overwhelmed by the complex and increased demands of the critically ill ward patient. The medical and nursing teams at the bedside are inexperienced and often unsupported by senior clinical decision-makers. This is dealt with by 'passing the buck' creating gaps and delays in care management which are the problems addressed by the outreach contribution. Outreach may solve problems for the critically ill ward patient, but the underlying causes remain poorly understood. [ABSTRACT FROM AUTHOR]

The propagules of most species of reef fish are advected from the reef, necessitating a return to reef habitats at the end of the pelagic stage. There is increasing evidence of active attraction to the reef but the sensory abilities of reef fish larvae have not been characterized well enough to fully identify cues. The electrophysiological methods of auditory brainstem response (ABR) and electroolfactogram (EOG) were used to investigate auditory and olfactory abilities of pre- and post-settlement stages of a damselfish, Pomacentrus nagasakiensis (Pisces, Pomacentridae). Audiograms of the two ontogenetic stages were similar. Pre-settlement larvae heard as well as their post-settlement counterparts at all but two of the tested frequencies between 100 Hz and 2,000 Hz. At 100 and 600 Hz, pre-settlement larvae had ABR thresholds 8 dB higher than those of post-settlement juveniles. Both stages were able to detect locally recorded reef sounds. Similarly, no difference in olfactory ability was found between the two ontogenetic stages. Both stages showed olfactory responses to conspecifics as well as L-alanine. Therefore, the auditory and olfactory senses have similar capabilities in both ontogenetic stages. Settlement stage larvae of P. nagasakiensis can hear and smell reef cues but it is unclear as to what extent larvae use these sounds or smells, or both, as cues for locating settlement sites. [ABSTRACT FROM AUTHOR]

Bioenergetic models frequently rely on published values or models for estimating the energy density of fish, principally because of the cost and effort of obtaining direct measurements. In this study, we developed empirical models of energy density for free-ranging juvenile coho salmon Oncorhynchus kisutch and Chinook salmon O. tshawytscha sampled at sea from the west coast of Oregon to Kodiak Island, Alaska, and we evaluated the accuracy of published energy density models commonly used for these species. Our analyses showed that the energy density of juvenile coho and Chinook salmon was strongly correlated to percent dry weight and proximate constituents (especially lipid and, to a lesser extent, protein concentrations) but poorly correlated to body size and condition factor. Percent dry weight of whole fish was the single best predictor of energy density for both species, accounting for more than 90% of the variance in energy density. We also found that percent dry weight in the muscle tissue accounted for 65% of the variance in energy density. Changes in energy density mainly reflected changes in lipid composition. These results indicate that accurate estimates of energy density could be obtained at low effort and cost for juvenile coho and Chinook salmon simply by determining the water contents in whole-fish or muscle samples. Published models overestimate the energy density of juvenile coho and Chinook salmon collected from the Pacific Ocean. This may result from the extrapolation of the models to different size-classes, life stages, or habitats. More caution is needed when models are extrapolated to conditions beyond those that were used for their development. [ABSTRACT FROM AUTHOR]

Depending on population, wild Fraser River sockeye salmon Oncorhynchus nerka travel distances of <100 km to >1100 km and ascend elevations ranging from near sea-level to 1200 m to reach spawning areas. Populations embarking on distant, high elevation migrations ( i.e. Early Stuart, Chilko and Horsefly populations) began their upriver spawning migrations with higher densities of somatic energy ( c. 9·2 to 9·8 MJ kg−1) and fewer eggs ( c. 3200 to 3800) than populations making shorter, low elevation migrations ( i.e. Weaver and Adams; c. 7·1 to 8·3 MJ kg−1 gross somatic energy and c. 4300 to 4700 eggs). Populations making difficult upriver migrations also had morphologies that were smaller and more fusiform than populations making less difficult migrations, traits that may facilitate somatic energy conservation by reducing transport costs. Indeed, fish travelling long distances expended less somatic energy per unit of migratory difficulty than those travelling shorter distances (2·8 to 3·8 kJ v. 10–1400 kJ). Consistent with evolutionary theory, difficult migrations appear to select for energy efficiency but ultimately fish making more difficult migrations produce fewer eggs, even when differences in body length have been accounted for. Despite large among-population differences in somatic energy at the start of upriver migration, all populations completed migration and spawning, and subsequently died, with c. 4 MJ kg−1 of energy remaining, a level which may reflect a threshold to sustain life. [ABSTRACT FROM AUTHOR]

Two successive experiments were conducted in order to assess plasma free amino acid (FAA) profiles as a method for evaluating protein quality of fish feeds for Atlantic salmon, Salmo salar (L.). In experiment 1, the importance of meal size and inter-fish variation was assessed by using dorsal aorta cannulated fish and diets that contained different sources of fishmeal (menhaden versus herring) which in the case of herring, had been dried at either 70 or 100 °C. In experiment 2, an attempt was made to mimic a production situation by comparing the FAA profiles in salmon fed diets containing two commercially available fishmeals that had been produced in accordance with industrial standards (Norse-LT94® and NorSeaMink®; Norsildmel AL, Fyllingsdalen, Norway). FAA profiles in plasma 6 h after feeding were compared with feed true protein digestibility as determined in mink. Cannulated fish, held in individual tanks, were hand-fed twice daily to pellet rejection (satiety) and daily records of the actual rations consumed were maintained. A total of 24 different amino acids and other amino-containing compounds were detected using high-pressure liquid chromatography. Morning and evening meal size showed significant correlations. Meal size had a significant effect on blood levels of the majority of essential free amino acids (EAA) as well as the total sum of FAA (TFAA). In experiment 1, a marked inter-individual effect was found, possibly because of incipient sexual maturation. FAA profiles were therefore corrected for meal size by linear regression while repeated sampling via the permanently implanted cannula allowed paired comparisons of the different test diets, minimizing inter-individual variation. Significant differences in plasma FAA profile, EAA and TFAA were detected between fish fed all diets in both experiments. The preceding parameters for fish ingesting each feed were directly related to their respective mink protein digestibility in experiment 1, but not in experiment 2. Our results show that dietary protein quality can be differentiated by the aforementioned protocol, and by using fish with a low metabolic rate feed qualities could be ranked correctly as in experiment 1. [ABSTRACT FROM AUTHOR]

Abstract The objective of this study was to determine the effect of replacing fishmeal with high-fibre and low-fibre sunflower cakes (HFSC and LFSC) on whole body fatty acid composition in tilapia Oreochromis niloticus (Linn). Sex-reversed O. niloticus males with an initial weight of approximately 16g ± 0.95 (SD) were used. A control diet based on herring meal and soybean meal was formulated. Six test diets were formulated such that low-fibre (LF) and high-fibre (HF) sunflower cakes (SC) contributed 30%, 60% and 80% of the dietary protein, and the diets were designated as LFSC-30, LFSC-60, LFSC-80, HFSC-30, HFSC-60, and HFSC-80 respectively. All fish were held at 25–28°C. They were fed three times daily their prescribed experimental diets for 70 days. At the end of this period they were starved for 24 h and weighed. Five fish representing the average weight of each replicated group (n =3) were frozen in plastic bags at –22°C for determination of fatty acid composition. Fatty acids in the fish were significantly influenced by diet. Palmitic, oleic and linoleic acids were the most abundant fatty acids in both the diets and the fish. Linoleic acid (18:2 ω6) was the most abundant fatty acid in diets based on sunflower cake. The levels of this fatty acid were also higher in fish fed diets with high contents of the sunflower cakes (LFSC-60, LFSC-80 and HFSC-80) (31.3%, 34.7% and 29.7% respectively) than fish fed the control diet (13.8%). Percentages of long chain polyunsaturated acids of the ω-3 family viz., docosahexaenoic (22:6 ω3) and eicosapentaenoic (20:5 ω3) were low in the diets and in the fish bodies. Fish fed the control diet had a higher level of 22:6 ω3 than those fed the other diets. The possible implications of the preceding findings for human health will be discussed. [ABSTRACT FROM AUTHOR]

The effect of arbuscular mycorrhizal (AM) colonisation by Glomus clarum on fruit yield and water use efficiency (WUE) was evaluated in watermelon (Citrullus lanatus) cv. Crimson Sweet F1 under field conditions. Treatments were: (1) well-watered plants without mycorrhizae (WW-M), (2) well-watered plants with mycorrhizae (WW+M), (3) water- stressed plants without mycorrhizae (WS-M) and (4) water-stressed plants with mycorrhizae (WS+M). When soil water tension readings reached -20 and -50 kPa for well-watered (WW) and water-stressed (WS) treatments, respectively, irrigation was initiated to restore the top soil to near field capacity. Water stress reduced watermelon shoot and root dry matter, fruit yield, water use efficiency but not total soluble solids (TSS) in the fruit, compared with the non-stressed treatments. Mycorrhizal plants had significantly higher biomass and fruit yield compared to nonmycorrhizal plants, whether plants were water stressed or not. AM colonisation increased WUE in both WW and WS plants. Macro- (N, P, K, Ca and Mg) and micro- (Zn, Fe and Mn) nutrient concentrations in the leaves were significantly reduced by water stress. Mycorrhizal colonisation of WS plants restored leaf nutrient concentrations to levels in WW plants in most cases. This is the first report of the mitigation of the adverse effect of water stress on yield and quality of a fruit crop. [ABSTRACT FROM AUTHOR]

The apparent digestibility of protein, organic matter and energy of high-fibre and fibre-reduced sunflower cakes, Kenya's ‘omena’ fishmeal, anchovy fishmeal and wheat bran were investigated in tilapia Oreochromis niloticus (L.) fingerlings. The feeding values and protein qualities of the above ingredients were also determined at two dietary protein levels. Fourteen diets were formulated, and each was provided to three tanks containing 12 fish in Expt 1 (digestibility study) and 25 fish in Expt 2 (feeding trial). Water temperatures and dissolved oxygen concentrations were maintained above 26 °C and 5.5 mg L[sup -1] respectively. Anchovy and ‘omena’ fishmeals each had an apparent digestibility coefficient for protein (ADC-P) of 90%, whereas the fibre-reduced and high-fibre sunflower cakes had ADC-P values of 89% and 86%. Wheat bran had an ADC-P value of 75%, which was significantly lower than those found for the other test ingredients. Apparent digestibility coefficients for energy (ADC-E) and digestible energy values (DE) were 86% and 78% and 4003 kcal kg[sup -1] and 3624 kcal kg[sup -1] for anchovy and omena fishmeals respectively. The corresponding values for the plant protein sources were 42% and 30% and 2200 kcal kg[sup -1] and 1400 kcal kg[sup -1] for the fibre-reduced and high-fibre sunflower cakes respectively. Diets based on the fibre-reduced cake had higher levels of all amino acids than those based on the high-fibre cake. Fish fed diets with 30% protein gained 40 g and had a feed conversion ratio (FCR) of 1.87, whereas those fed diets with 20% protein gained 35 g and had a FCR of 2.2. The source of protein had a significant effect on weight gain. [ABSTRACT FROM AUTHOR]

Animals that thrive both on land and underwater are faced with the task of interpreting stimuli in different media. This becomes a challenge to the sensory receptors in that stimuli (e.g., sound, motion) may convey the same type of information but are transmitted with different physical characteristics. We used auditory brainstem responses to examine hearing abilities of a species that makes full use of these two environments, the American alligator (Alligator mississipiensis). In water, alligators responded to tones from 100 Hz to 2,000 Hz, with peak sensitivity at 800 Hz. In air, they responded to tones from 100 Hz to 8,000 Hz, with peak sensitivity around 1,000 Hz. We also examined the contribution to hearing of an air bubble that becomes trapped in the middle ear as the animal submerges. This bubble has been previously implicated in underwater hearing. Our studies show that the trapped air bubble has no affect on auditory thresholds, suggesting the bubble is not an important adaptation for underwater hearing in this species. [ABSTRACT FROM AUTHOR]

Objective: To investigate the role of haematological indices, socioeconomic status, and morbidity in prepubertal growth in homozygous sickle cell (SS) disease.Method: Height, weight, and haematology were serially recorded in a cohort study of 315 children with SS disease from birth to 9 years at the sickle cell clinic of the University Hospital of the West Indies, Kingston, Jamaica.Results: Height increment between 3 and 9 years correlated positively with total haemoglobin at age 7 years in boys but not girls. Attained height and weight at age 7 years correlated positively with haemoglobin and fetal haemoglobin in boys but not girls. Only the correlation between haemoglobin and weight showed a significant gender difference. Partial correlation analysis suggested that the effect of haemoglobin was accounted for by the effect of fetal haemolglobin and further analysis indicated that height correlated with F reticulocyte count (a measure of fetal haemoglobin production) in both sexes but not with the ratio of F cells to F reticulocytes (a measure of F cell enrichment). Growth was not significantly related to mean red cell volume, proportional reticulocyte count, alpha thalassaemia, socioeconomic status, or morbidity.Conclusion: A high concentration of fetal haemoglobin in boys with SS disease is associated with greater linear growth. It is postulated that in boys, low concentrations of fetal haemoglobin increase haemolysis and hence metabolic requirements for erythropoiesis, putting them at greater risk of poor growth. Differences in the relationship of haematology and growth between boys and girls with SS disease dictate that future analyses of growth take gender into account. [ABSTRACT FROM AUTHOR]

In the power set P(E) of a set E, the sets of a fixed finite cardinality k form a cross-cut, that is, a maximal unordered set C such that if X, Y ⊑E satisfy X⊑Y, X ⊑ some X′ in C, and Y⊑ some Y′ in C, then X⊑Z⊑Y for some Z in C. For E=ω, ω, and ω, it is shown with the aid of the continuum hypothesis that P(E) has cross-cuts consisting of infinite sets with infinite complements, and somewhat stronger results are proved for ω and ω. [ABSTRACT FROM AUTHOR]